Peep

is the peep, a threat to push through on the next move. A peep is a type of forcing move, where White hopes to gain some advantage by being able to play in sente (by forcing Black to connect at a). The advantage could be anything from simply having the stone in place, to destroying Black's eyeshape, to breaking a ladder, to protecting her own position.

Peep

here is also a peep, threatening to cut at a. But White should make sure her peep is not aji-keshi--in other words, removing the future possibility of cutting directly at a, if, for instance, the ladder becomes favorable. Such a move might be a raw peep; see also do not peep at cutting points.

Peep

Although the proverb states that even a moron connects against a peep, as with any forcing move, it is natural to want to consider less submissive responses, including ones that will not end in gote. Depending on circumstances, any of the circled points might be a possible response. See below for another example.

With a standard tesuji?

I saw this siuation in a game and it was handled like this instead of just blocking at a. This was described to be a standard tesuji.. Any comments on it? - Reuven

Ninten:I'm only about 19 kyu but I think it's a standard tesuji because it reduces the opponents territory and also if the opponent attacks at a (uselessly) it gains a 'free' move

tapir: This looks like a sente sequence because of , but has no relation to the peep at all, as white is alive without. Charles' sequence below makes more sense, imho.

Charles I remember something written in an old BGJ - in reply to a pro saying a play was standard, an amateur 2 dan saying he wished he could find such things in a game.

With a standard tesuji? (ii)

Here the point is that can be played, but then after , White has big worries about Black at b later. If White plays b to capture, right now, then the peep at turned out to be gote, so Black will be happy.

With a standard tesuji? (iii)

One variation: White gets into big trouble.

As alternatives to peep, the forms peek or poke are also seen, but discouraged. Poke would be better used for a thrusting through, or tsukidashi:

Poke

Could you explain a difference between the usage of 刺 ci4 - peep and 觑 qù peep ?

unkx80: Don't think there is a lot of different where usage in Go is concerned... but I almost never see 觑 in everyday usage, whereas 刺 is very common.